doing mitzvos because they make sense

1) Rashi addresses why the command אִ֣ישׁ אִמּ֤וֹ וְאָבִיו֙ תִּירָ֔אוּ וְאֶת־שַׁבְּתֹתַ֖י תִּשְׁמֹ֑רוּ ends off אֲנִ֖י ה׳ אֱלֹקיכֶֽם.  You can say about every mitzvah אֲנִ֖י ה׳ אֱלֹקיכֶֽם who is giving the tzivuy, so why mention it here?  Rashi says the pasuk is mechadesh that if your parent tells you to do an aveira, you don't have to listen because אֲנִ֖י ה׳ אֱלֹקיכֶֽם overrides the command to listen to them.  There is a hierarchy of who you need to listen to.  Abarbanel suggests that the Torah is teaching us a fundamental yesod here. The mitzvah of kibud av is a basic, moral imperative that any ethical person can appreciate.  Chazal tell us that Eisav excelled in the mitzvah of kibud av.  The gemara (Kid 31) tells a story about a non-Jew, Dama ben Nesina, who refused to wake his father even if it meant giving up a lucrative sale.  The same is true about having a day of shabbos, a day off from work.  It's common sense that workers need a break.  True, no other nation has rules saying things like you can't turn on a light on the weekend, but they appreciate the general concept of a day of rest.  The same in fact can be said about many of the being adam l'chaveiro laws in parshas Kedoshim -- these are norms of basic morality that all people subscribe to -- but it all starts with shabbos and kibud av.  Therefore, the Torah jumps in and tells us אֲנִ֖י ה׳ אֱלֹקיכֶֽם.  The reason you have to obey these principles is not because they make sense, not because it's what all people do, not because there is some ethical principle behind them, but rather simply because Hashem commanded them, because אֲנִ֖י ה׳ אֱלֹקיכֶֽם.  

In the aseres hadibros the mitzvah of kibud av v'eim (Shmos 20:11) has a promise of reward  כַּבֵּ֥ד אֶת־אָבִ֖יךָ וְאֶת־אִמֶּ֑ךָ לְמַ֙עַן֙ יַאֲרִכ֣וּן יָמֶ֔יךָ עַ֚ל הָאֲדָמָ֔ה אֲשֶׁר־ה׳ אֱלֹקיךָ נֹתֵ֥ן לָֽךְ׃, that we should have a long life in Eretz Yisrael.  Why does the Torah specifically mention the reward?  Netziv quotes a principle that Ramban elaborates on in our parsha of Acharei Mos.  Ramban holds that fundamentally, mitzvos are meant to be done in Eretz Yisrael.  Not just mitzvos ha'teluyos ba'aretz, but all mitzvos.  However, if we had nothing to do in galus, it would not be so easy to retain our identity or even to know what to do and how to do it when we return to the land.  The Torah therefore commands us to do mitzvos that are not teluyos ba'aretyz even in chu"l so that we remain in practice and have the necesssry training so we can do them properly when G-d willing we come back to Eretz Yisrael.  

I would have thought, says the Netziv, that this Ramban is talking only about mitzvos bein adam lamakom like putting on tefillin, wearing tzitzis, etc.  However, when it comes to mitzvos bein adam l'chaveiro, like kibud av, like v'ahavta l'reiacha, etc., what difference does it make whether I am in Eretz Yisrael or in chu"l -- those mitzvos should apply equally at all times and places, with no distinction.  That's why, says Netziv, the pasuk tacks on that the reward for kibuv av is  לְמַ֙עַן֙ יַאֲרִכ֣וּן יָמֶ֔יךָ עַ֚ל הָאֲדָמָ֔ה.  The Torah is showing us that even a mitzvah sichlis like kibid av that you think would apply equally everywhere is still is fundamentally connected to Eretz Yisrael and its reward can be gleaned more easily and in greater abundance only in Eretz Yisrael.  Logically, it makes no sense, and that gufa is the point -- the mitzvos, even those that make sense to us, transcend logic.  Netziv writes: משום הכי כתיב במצוה זו של כיבוד אב ואם גם כן ״על האדמה״ ללמדנו דאחר שהיא מצות עשה הכתובה בתורה הרי היא ככל חוקי התורה שאין בהם טעם ושכל אנושי

That's the same point the Abarbanel is making.  Yes, kibud av is something that makes sense to do; yes, having a weekend break makes sense.  But that's not why you should keep the mitzvos. אֲנִ֖י ה׳ אֱלֹקיכֶֽם, irrespective of what makes sense or doesn't make sense.

(Abarbanel frequently addresses himself to the Rambam's rationalizations of mitzvot.  It would be interesting to do a fuller study of his attitude toward taamei hamitzvot and rationalism in general, but that's beyond a blog post.)

2) While on the topic of Abarbanel: the pasuk writes with respect to a person who gives his children over to Molech that  עַ֥ם הָאָ֖רֶץ יִרְגְּמֻ֥הוּ בָאָֽבֶן (20:2).  Abarbanel suggests that this phrase may mean אולי שכיון הכתוב בזה שמבלי התראה ולא חקירת ב״ד ירגמוהו.  I am not aware of a makor that no hasra'as is required here or no chakiras eidim is required, but if anyone knows of one, let me know, otherwise I imagine you have to say Abarbanel simply means this is something you might deduce based on peshuto shel mikra.